title: The Arabidopsis adaptor protein AP-3μ interacts with the G-protein β subunit AGB1 and is involved in abscisic acid regulation of germination and post-germination development.
abstract: Heterotrimeric G-proteins (G-proteins) have been implicated in ubiquitous signalling mechanisms in eukaryotes. In plants, G-proteins modulate hormonal and stress responses and regulate diverse developmental processes. However, the molecular mechanisms of their functions are largely unknown. A yeast two-hybrid screen was performed to identify interacting partners of the Arabidopsis G-protein β subunit AGB1. One of the identified AGB1-interacting proteins is the Arabidopsis adaptor protein AP-3µ. The interaction between AGB1 and AP-3µ was confirmed by an in vitro pull-down assay and bimolecular fluorescence complementation assay. Two ap-3µ T-DNA insertional mutants were found to be hyposensitive to abscisic acid (ABA) during germination and post-germination growth, whereas agb1 mutants were hypersensitive to ABA. During seed germination, agb1/ap-3µ double mutants were more sensitive to ABA than the wild type but less sensitive than agb1 mutants. However, in post-germination growth, the double mutants were as sensitive to ABA as agb1 mutants. These data suggest that AP-3µ positively regulates the ABA responses independently of AGB1 in seed germination, while AP-3µ does require AGB1 to regulate ABA responses during post-germination growth.
authors.affiliation: Asian Natural Environmental Science Center, The University of Tokyo, Nishitokyo, Tokyo 188-0002, Japan.
authors.forename: Jeeraporn
authors.initials: J
authors.lastname: Kansup
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsugama
authors.forename: Shenkui
authors.initials: S
authors.lastname: Liu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Takano
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000502:physiology*; D009154:Mutation; D010641:Phenotype
chemical_list: C089590:AGB1 protein, Arabidopsis; C000590919:AP-3mu protein, Arabidopsis; D048868:Adaptor Proteins, Signal Transducing; D029681:Arabidopsis Proteins; D044387:GTP-Binding Protein beta Subunits; D000040:Abscisic Acid
keywords: Abscisic acid; Arabidopsis; G-protein; adaptor protein; germination; post-germination growth.